lib/string.c: improve strrchr()

Instead of potentially passing over the string twice in case c is not
found, just keep track of the last occurrence.  According to
bloat-o-meter, this also cuts the generated code by a third (54 vs 36
bytes).  Oh, and we get rid of those 7-space indented lines.
Signed-off-by: NRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

lib/string.c

@@ -313,12 +313,12 @@ EXPORT_SYMBOL(strchrnul);
  */
 char *strrchr(const char *s, int c)
 {
-       const char *p = s + strlen(s);
-       do {
-           if (*p == (char)c)
-               return (char *)p;
-       } while (--p >= s);
-       return NULL;
+	const char *last = NULL;
+	do {
+		if (*s == (char)c)
+			last = s;
+	} while (*s++);
+	return (char *)last;
 }
 EXPORT_SYMBOL(strrchr);
 #endif